Selenium heterocycles XXV. Synthesis of thieno[3,4-d][1,2,3]-thiadiazole,selenolo[3,4-d][1,2,3]thiadiazole and pyrrolo[3,4-d][1,2,3]-thiadiazole. Three novel ring systems

Starting from the readily available 4-bromomethyl-5-benzoyl-1,2,3-thiadiazole and 5-bromomethyl-4-benzoyl-1,2,3-thiadiazole; thieno3,4-d]1,2,3]thiadiazole, selenolo3,4-d]1,2,3]-thiadiazole and pyrrolo3,4-d]1,2,3]thiadiazole were synthesized in good yield.